Recently, high-speed, mass transmission has been desired in various user environments such as the public, office, and home environments, and wireless LAN (Local Area Network) technology has received much attention as such data transmission technology. Standardization activities of wireless LANs are being promoted such as high-performance LAN (High Performance Local Area Network) or IEEE802.11 systems.
The high-performance wireless LANs are a master-slave type network in which a communication terminal accommodation device performs centralized control so that a plurality of communication terminals will communicate with the communication terminal accommodation device. Specifically, as shown in FIG. 19, an access point (AP) 1901 as the communication terminal accommodation device performs centralized control relating to communication with mobile terminals (MTs) 1902 and 1903. When the MTs 1902 and 1903 communicate with each other, the communication is always carried out through the AP 1901.
The IEEE802.11 systems are a direct connection network, and are defined as a centralized control type (Point Coordination Function: PCF) and a distributed control type (Distributed Coordination Function: DCF). As shown in FIG. 20A, the centralized control type is such that a point coordinator (PC) 2001 with control capabilities performs centralized control relating to communication with stations (STAs) 2002 and 2003. Therefore, when the STAs 2002 and 2003 communicate with each other, the communication is always carried out through the PC 2001.
On the other hand, the distributed control type is such that, as shown in FIG. 20B, each of STAs 2004 to 2006 performs carrier sense before data transmission so that it initiates communication after making certain a transmission medium is vacant.
Thus the high-performance LANs and IEEE80802.11 are standardized as separate wireless LAN systems.
As matters now stand, however, even wireless LANs cannot enable communication between communication terminals in different systems. In other words, MT under the control of AP and STA under the control of PC cannot communicate with each other.